Nitric oxide protects Cu,Zn-superoxide dismutase from hydrogen peroxide- induced inactivation

Yu Shin Kim, Sanghwa Han

Research output: Contribution to journalArticle

17 Scopus citations


Reaction of Cu,Zn-superoxide dismutase (SOD1) and hydrogen peroxide generates a putative oxidant SOD-Cu2+-(·)OH that can inactivate the enzyme and oxidize 5,5'-dimethyl-1-pyrroline-N-oxide (DMPO) to DMPO-(·)OH. In the presence of nitric oxide ((·)NO), the SOD1/H2O2 system is known to produce peroxynitrite (ONOO-). In contrast to the proposed cytotoxicity of (·)NO conferred by ONOO-, we report here a protective role of (·)NO in the H2O2-induced inactivation of SOD1. In a dose-dependent manner, (·)NO suppressed formation of DMPO-(·)OH and inactivation of the enzyme. Fragmentation of the enzyme was not affected by (·)NO. Bicarbonate retarded formation of ONOO-, suggesting that (·)NO competes with bicarbonate for the oxidant SOD-Cu2+-(·)OH. We propose that (·)NO protects SOD1 from H2O2- induced inactivation by reducing SOD-Cu2+-(·)OH to the active SOD-Cu2+ with concomitant production of NO+ which reacts with H2O2 to give ONOO-. (C) 2000 Federation of European Biochemical Societies.

Original languageEnglish (US)
Pages (from-to)25-28
Number of pages4
JournalFEBS Letters
Issue number1-2
StatePublished - Aug 11 2000
Externally publishedYes



  • Cu,Zn-superoxide dismutase
  • Hydrogen peroxide
  • Nitric oxide

ASJC Scopus subject areas

  • Biochemistry
  • Biophysics
  • Molecular Biology

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